Concept explainers
Consider a galvanic cell composed of the SHE and a half-cell using the reaction Ag+(aq) + e− → Ag(s). (a) Calculate the standard cell potential. (b) What is the spontaneous cell reaction under standard-state conditions? (c) Calculate the cell potential when [H+] in the hydrogen electrode is changed to (i) 1.0 × 10−2 M and (ii) 1.0 × 10−5 M, all other reagents being held at standard-state conditions. (d) Based on this cell arrangement, suggest a design for a pH meter.
(a)
Interpretation:
The standard electrode potential of the given cell and the spontaneous chemical reaction in the cell has to be found. The cell potential of the given cell has to be found with the different concentrations of the hydrogen ion and a design for the
Concept Introduction:
Galvanic cell is an electrochemical cell which converts the chemical energy of a reaction into electrical energy.
Standard hydrogen electrode (SHE) is a reference electrode whose potential is considered to be zero volts. The potential of any other electrode is found by comparing with the SHE.
The standard electrode potential of a cell
Nernst equation is one of the important equations in electrochemistry. In Nernst equation the electrode potential of a cell reaction is related to the standard electrode potential, concentration or activities of the species that is involved in the chemical reaction and temperature.
Where,
At room temperature
Answer to Problem 18.76QP
The standard electrode potential of the cell is found to be
Explanation of Solution
To calculate the standard electrode potential of the cell
The standard electrode potential of the cell is the difference in standard electrode potential of the cathode and anode.
In order to determine the standard electrode potential we need to find out the half cell reactions in the cathode and anode of the given electrode.
The half cell reactions are
The standard electrode potential is calculated as given below
(b)
Interpretation:
The standard electrode potential of the given cell and the spontaneous chemical reaction in the cell has to be found. The cell potential of the given cell has to be found with the different concentrations of the hydrogen ion and a design for the
Concept Introduction:
Galvanic cell is an electrochemical cell which converts the chemical energy of a reaction into electrical energy.
Standard hydrogen electrode (SHE) is a reference electrode whose potential is considered to be zero volts. The potential of any other electrode is found by comparing with the SHE.
The standard electrode potential of a cell
Nernst equation is one of the important equations in electrochemistry. In Nernst equation the electrode potential of a cell reaction is related to the standard electrode potential, concentration or activities of the species that is involved in the chemical reaction and temperature.
Where,
At room temperature
Answer to Problem 18.76QP
The spontaneous reaction taking place in the cell is the reduction of silver ion and oxidation of hydrogen gas.
Explanation of Solution
To write the spontaneous cell reaction under the given standard conditions
In the given cell composed of standard hydrogen electrode and silver electrode, The silver ions in the solution will be reduced into solid silver and the hydrogen molecules will be oxidised into hydrogen ions.
(c)
Interpretation:
The standard electrode potential of the given cell and the spontaneous chemical reaction in the cell has to be found. The cell potential of the given cell has to be found with the different concentrations of the hydrogen ion and a design for the
Concept Introduction:
Galvanic cell is an electrochemical cell which converts the chemical energy of a reaction into electrical energy.
Standard hydrogen electrode (SHE) is a reference electrode whose potential is considered to be zero volts. The potential of any other electrode is found by comparing with the SHE.
The standard electrode potential of a cell
Nernst equation is one of the important equations in electrochemistry. In Nernst equation the electrode potential of a cell reaction is related to the standard electrode potential, concentration or activities of the species that is involved in the chemical reaction and temperature.
Where,
At room temperature
Answer to Problem 18.76QP
(i) The electrode potential, when the concentration of hydrogen ion is
(ii) The electrode potential, when the concentration of hydrogen ion is
Explanation of Solution
(i)
To calculate the electrode potential when the concentration of hydrogen ion is
The electrode potential of the cell can be calculated using the Nernst equation.
Where,
In the standard state all the species will have concentration equal to unity. In this case only the concentration of hydrogen ion is changed. On plugging in the concentration of the oxidised and reduced species to the given equation the electrode potential of the cell can be calculated.
(ii)
To calculate the electrode potential when the concentration of hydrogen ion is
The electrode potential of the cell can be calculated using the Nernst equation.
Where
In the standard state all the species will have concentration equal to unity. In this case only the concentration of hydrogen ion is changed. On plugging in the concentration of the oxidised and reduced species to the given equation the electrode potential of the cell can be calculated.
(d)
Interpretation:
The standard electrode potential of the given cell and the spontaneous chemical reaction in the cell has to be found. The cell potential of the given cell has to be found with the different concentrations of the hydrogen ion and a design for the
Concept Introduction:
Galvanic cell is an electrochemical cell which converts the chemical energy of a reaction into electrical energy.
Standard hydrogen electrode (SHE) is a reference electrode whose potential is considered to be zero volts. The potential of any other electrode is found by comparing with the SHE.
The standard electrode potential of a cell
Nernst equation is one of the important equations in electrochemistry. In Nernst equation the electrode potential of a cell reaction is related to the standard electrode potential, concentration or activities of the species that is involved in the chemical reaction and temperature.
Where,
At room temperature
Answer to Problem 18.76QP
The given cell is sensitive to the hydrogen in concentration. Hence it can be used as the
Explanation of Solution
To suggest a design for a
From the results obtained in the question (c) it is clear that the given cell itself can be used as a
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Chapter 18 Solutions
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